The proposed objective of the proposed research is to isolate from plants of the family Compositae new compounds which may have antitumor or other biological properties. Emphasis will continue to be placed on sesquiterpene lactones because this class of secondary metabolites exhibits a wide spectrum of biological action, in particular cytotoxic and antitumor activity, and is frequently responsible for the antifeeding, insect deterrent, mutagenic, allergenic and growth inhibitory properties of the plants in which they occur, because a larger selection of these compounds could contribute to increased knowledge of the relationship between structure and activity, because knowledge of their distribution is useful in clarifying evolutionary relationships within Compositae and because knowledge of their stereochemistry provides important information on the operation of the mevalonate pathway of terpene biosynthesis. Many of the plants to be studied are used as medicinal plants in the countries of their origin or are closely related to species which have already furnished extracts. Structures will be elucidated by chemical and instrumental methods. New compounds will continue to be submitted to the anticancer screen of the National Cancer Institute.